This invention relates to an electrolytic capacitor unit for an audio apparatus, and more particularly to an electrolytic capacitor unit for an audio apparatus with a low internal resistance especially suitable for a power source filter in an audio apparatus loaded in a car (car audio apparatus).
Most of car audio apparatus are powered by car batteries (12V power source in Japan, for example). In order to improve sound quality, a capacitor is connected as a filter for a smoothing power source between a battery and a power amplification.
When a battery loaded on a car is 12V, an electrolytic capacitor with a rating of 16V or more and about 1 F is utilized as a power source filter. Conventionally one large-sized electrolytic capacitor with a shaft length of 120 mm and a diameter of 76 mm approximately, for example, is utilized for a high-volume capacitor.
The large-sized electrolytic capacitor, however, has an internal resistance as high as 1.8 mxcexa9, thus causing a change in an output voltage and making reproduction of high-quality sound difficult.
The present invention has been made to solve the above-described disadvantage. An object of the present invention is to provide an electrolytic capacitor unit for an audio apparatus, in which in addition to a large capacitance necessary for a power source filter for an audio apparatus loaded in a car, a sufficiently low internal resistance and stable output voltage can be obtained.
According to the present invention, in an electrolytic capacitor unit for an audio apparatus utilized as a power source filter in an audio apparatus loaded in a car, a power source of which is supplied from a battery with a rated voltage of 12V or more, a given number of aluminum electrolytic capacitors with the same rating is connected in parallel to gain a capacitance of 1 F (farad) or more and an internal resistance of less than 1.0 mxcexa9 as a whole, so that the object can be achieved.
In the case above, the whole given number of the aluminum electrolytic capacitors can be mounted on one circuit substrate. But to keep them in a smaller place, the aluminum electrolytic capacitors are preferably divided into more than one group and each group is mounted on an individual circuit substrate.
The aluminum electrolytic capacitors, for example, are divided into four groups. Each group with a capacitance of about 0.25 F and an internal resistance of less than 4.0 mxcexa9 is mounted on an individual circuit substrate. The four groups, that is, four circuit substrates can be connected in parallel.
Similarly, the aluminum electrolytic capacitors are divided into two groups. Each group with a capacitance of about 0.5 F and an internal resistance of less than 2.0 mxcexa9 is mounted on an individual circuit substrate. The two groups, that is, two circuit substrates can be connected in parallel.
In addition, the aluminum electrolytic capacitors are divided into a first group and a second group. The first group has a capacitance of about 0.75 F and an internal resistance of less than 1.5 mxcexa9 and the second group has a capacitance of about 0.25 F and an internal resistance of less than 4.0 mxcexa9. Each group is mounted on an individual circuit substrate. The circuit substrates of the first and the second groups can be connected in parallel.
As described above, according to the present invention, an electrolytic capacitor unit for an audio apparatus with a capacitance of 1 F and an internal resistance of less than 1.0 mxcexa9 is obtained, thus improving voice band, sound sensation, sound resolution, sound image, and sound field, whereby high-grade reproduced sound can be obtained.